The invention relates to a cooling grate for bulk material, having a carrying plate for accommodating a layer of the material for cooling, and having conveying elements by means of which the material for cooling is transported in a conveying direction on the resting carrying plate and which has pushers, which are arranged in a movable manner on that side of the carrying plate which is subjected to the action of the material for cooling, and a drive, which is arranged on the other side of the carrying plate and is intended for executing a lifting movement, each pusher being assigned an opening in the carrying plate and a transmission member, which is guided thereby and connects the pusher to the drive.
Cooling grates which are constructed as a push grate comprising a plurality of rows, running transversely to the conveying direction, of grate plates which are alternately arranged in a fixed manner and such that they can be moved back and forth in the conveying direction are known. The material for cooling is transported in the conveying direction by the reciprocating movement of the movable grate plates. On account of some of the grate plates being arranged in a movable manner, the operation of supplying them with cooling gas involves high outlay. Moreover, the movable grate plates are subjected to considerable wear. Also known are cooling grates in which the material is advanced on a stationary carrying plate by a conveying system. The conveying system has pushers which run transversely to the conveying direction and are either moved continuously in the conveying direction or are driven in a reciprocating manner. The invention is concerned with the construction with reciprocating pushers.
U.S. Pat. No. 3,010,218 discloses a cooling grate of this type, in the case of which there is arranged on the carrying plate, which bears the material for cooling, a row of pushers which are shaped in a wedge-like manner and can be moved back and forth along the surface of the carrying plate. Beneath the pushers, openings, through which a respective bolt is guided, are provided in the carrying plate in each case. This bolt has its top end arranged on the pusher and its bottom end arranged on the drive frame. The bolts serve for transmitting the reciprocating movement of the drive frame to the pushers. A similar cooling grate is known from U.S. Pat. No. 2,904,323. The disadvantage with these known cooling grates is that the pushers have an insufficient conveying action and the quantity of material for cooling which falls through the openings is undesirably high.
In the case of the cooling grate according to WO 98/48231, the pushers are arranged such that they can be moved back and forth. The drive frame for the pushers is arranged beneath the carrying plate. In order to connect the drive frame to the pushers, two parallel transmission plates are provided, these extending in the conveying direction over the entire length of the carrying plate, having their bottom end connected to the drive frame and having the pushers arranged at their top end. In order for it to be possible for the transmission plates to be guided from the pushers on the top side to the drive frame on the underside of the carrying plate, the latter is provided with corresponding slots which run in the conveying direction and likewise extend in the conveying direction over the entire length of the carrying plate. The carrying plate has upright panels extending laterally on the slots in the direction of the pushers. Arranged on the top side of the transmission plate is a U-profile, of which the legs extend in the direction of the carrying plate and engage over the upright panels. The gap which is produced here between the legs of the U-profile and the upright panels is intended to serve as sealing in relation to material for cooling penetrating into the slot through the cooling grate. The disadvantage with this known cooling grate is that, as a result of the slots extending over the entire length of the cooling grate, it is not possible for any cooling gas to be blown through the cooling grate at these locations. The material for cooling which is located above the slots and/or the transmission plates is thus only cooled to an insufficient extent. This results in an undesirably non-uniform cooling result. It is also disadvantageous that the transmission plate passes through all the temperature zones of the cooling grate and is thus exposed to pronounced thermal stressing, which may result in non-uniform warping of the transmission plate.
Taking U.S. Pat. No. 3,010,218 as the departure point, the object of the invention is to provide a cooling grate with a conveying system of the type mentioned in the introduction in the case of which the mixing action and the sealing in relation to material for cooling falling through are improved, without this adversely affecting the cooling result in the process.